1. Field of the Invention
The present invention relates to a liquid jet recording head and a liquid jet recorder having the same, and more particularly to a liquid jet recording head having means for forming recording liquid droplets and a liquid jet recorder having such a liquid jet recording head.
2. Description of the Prior Art
A liquid jet recording head applied to a liquid jet recording system usually has a fine liquid discharging orifice, a liquid path and a liquid discharge energy generator arranged in the liquid path.
In the past, the liquid jet recording head has been manufactured in one of the following methods. (1) A fine groove is formed in a glass, ceramic or metal plate by grinding or etching and the plate is joined with another appropriate plate to form a liquid path. (2) A liquid path wall made of a photo-sensitive resin hardened film is formed on a substrate on which a liquid discharge energy generator is arranged, and the path is covered by a cover. (See Japanese Patent Laid-open Application No. 43876/1982). (3) A plate member having a liquid path wall formed by plating or resin molding is bonded to a substrate on which a liquid discharge energy generator is arranged.
Two or more liquid jet recording heads manufactured in the method described above are arranged in parallel and fixed to manufacture a multi-orifice liquid jet recording head, in a manner shown in FIGS. 1 to 4.
Numeral 1 denotes an orifice, numeral 3 denotes a liquid supply tube, numeral 31 denotes an individual liquid jet recording head having the orifice and the liquid supply tube, numeral 32 denotes a support plate, numeral 33 denotes a fixing bolt, numeral 34 denotes a groove (recess), numeral 35 denotes a fixing plate and numeral 36 denotes a positioning abutment.
(1) In FIG. 1, the individual liquid jet recording heads 31 are fixed on the support plate 32 by the bolts 33.
(2) In FIG. 2 the recesses 34 into which the individual liquid jet recording heads are to be fitted are formed in the support plate 32, and the liquid jet recording head are fitted to the recesses 34. They may be fixed by adhesive material if required.
(3) In FIG. 3, the individual liquid jet recording heads are arranged on the support plate 32 and the heads are pressed by the fixing plate 35.
(4) In FIG. 4, the positioning projections 36 are formed on the support plate 32 and the individual liquid jet recording heads are abutted thereto and fixed by bolts or adhesive material.
However, the above methods for arranging and fixing the liquid jet recording heads have the following disadvantages.
(1) When the individual liquid jet recording heads are arranged to form a multi-orifice head, the positioned relation of those individual liquid jet recording head has a significant effect on a recording quality (e.g. print quality). Accordingly, they must be positioned and fixed at a high precision. When they are arranged and fixed in the manner described above, the positions of the holes for the bolts in the fixing plate, the grooves (recesses) or the abutting projections must be manufactured with a high precision. As a result, the cost of the support plate increases and mass-production is not appropriate.
(2) If a mechanism (not shown) for finely adjusting the positions of the individual heads after the arrangement thereof in order to attain a high precision in the positional relation of the liquid jet recording heads, the cost further increases and the positioning process is complex.
In another prior art liquid jet recorder having the recording head shown in FIG. 5, an ink supply tube 502 is connected to a recording head 501, and ink 504 is supplied from an ink container 503 and reaches an end of the recording head 501. As an electrical signal is applied to a piezo-electric element arranged in the recording head, ink droplets 505 are discharged from the end or nozzle of the recording head 501 so that characters are printed on a record medium 506.
However, since the recording head 501 and the ink container 503 are connected through the ink supply tube 502, it is difficult to exchange the record head 501 when it fails. The small diameter tube used as the ink supply tube 502 has a sufficient length to be reciprocally moved with the carriage. Accordingly, a large space is required to allow the tube to be moved with the carriage.
In order to resolve the above problem, a liquid jet recorder shown in FIG. 6 has been proposed. A recording head 601 and an ink container 602 are in union to form a recording head unit 603 which is removably attached to a carriage 604. Ink in the ink container is discharged as ink droplets 606 from a nozzle 605 by a discharge energy generated by a piezo-electric element or a heat generating resistor arranged in the recording head 601. Numeral 607 denotes a slide shaft fixed to a printer body. The carriage 604 reciprocates along the slide shaft.
In such a prior art recorder, the positioning of the recording head unit 603 to the carriage 604 is done only by fixing means which fixes the head unit to the carriage 604. When a plurality of head units are mounted on the carriage, the positioning of the head units is done for each head unit by fixing it to the carriage. As a result, the alignment of the head units is not precise. When high density recording or color recording is to be done, the reach points on the record medium of the ink droplets discharged from the head units deviate from each other due to the misalignment of the head units and hence a high quality record is not attained.
As described above, such a liquid jet recording head may be manufactured by forming fine grooves on the glass or metal plate by grinding or etching, and joining the grooved plate to another appropriate plate to form the liquid paths.
In the head manufactured by the prior art method, roughness in the ground liquid path inner wall is too high or the liquid path has a strain due to a difference between etching rates. Accordingly, it is difficult to form a high precision liquid path and the liquid discharge characteristics of the recording heads thus manufactured are not uniform.
In the grinding step, the plate may be scratched or broken. Thus, a manufacturing yield is low. When the etching process is used, the number of manufacturing steps increases and the manufacturing cost increases.
As a common disadvantage to the prior art methods described above, it is difficult to precisely position the grooved plate having the liquid paths formed therein to the plate having the liquid discharge energy generator such as piezo-electric element or heat generating element arranged therein. Accordingly, mass-production is hardly attained.
In the liquid jet recording head manufacturing method, for example, disclosed in Japanese Patent Laid-open Application No. 43878/1982, a liquid path wall made of a photo-sensitive resin hardened film is formed on a substrate on which a liquid discharge energy generator is mounted, and a cover for the liquid path wall is formed.
The liquid jet recording head having the ink path wall made of the photo-sensitive resin hardened film, is excellent in that it resolves the finish precision of the liquid path, the complexity of the manufacturing process and the low manufacturing yield in the prior art liquid jet recording head.
The photo-sensitive resin may be one of those used in the field of photo-lithography such as photo-resist. For example, it may be diazo resin, P-diazo quinone, photo-polymer which uses vinyl monomer and polymerization initiator, double photopolymer which uses polyvinyl cinnamate and sensitizer, mixture of orthonaphthoquinone diazide and novolak type phenol resin, mixture of polyvinyl alcohol and diazo resin, polyether type photo-polymer of 4-glycydil ethylenoxid and benzophenone or glycydil calcon, copolymer of N,N-dimethyl methacryl amide and acryl amide benzophene, unsaturated polyester photo-sensitive resin (e.g. APR (Asahi Kasei), Tevista (Teijin), Zonne (Kansai Paint)), unsaturated urethane oligomer photo-sensitive resin, photo-sensitive composition of bifunctional acrylic monomer, polymerization initializer and polymer, dichromate photo-resist, non-chrome-aqueous photo-resist, poly-cinnamic acid vinyl photo-resist, or cyclized rubber-azido photo-resist.
In addtion, DuPont 110-manent photo-polymer coating, RISTON, and solder masks 730S, 740S, 730FR, 740FR and SM1 may be used.
However, most of the aforementioned-photo-sensitive resins and commercially available resins are blue or red and none of the photo-sensitive resins has two or more colors of dyes or pigments added in the resin. Accordingly, the following disadvantages are encountered.
(1) In the manufacturing process of the liquid jet recording head, if two or more liquid jet recording heads are to be arranged to manufacture a multi-color liquid jet recording head, the monochromatic liquid jet recording heads are arranged in parallel and liquids of desired colors are injected to the respective heads. However, because the colors of the respective liquid jet recording heads are similar (the colors of the photo-sensitive resins are most distinctive), it is difficult to discriminate the heads and incorrect liquid may be injected to the head.
(2) In the recording head manufacturing process of the multi-color recording head having two or more recording heads arranged, when the heads for the respective colors have slight differences in the shape but do not have distinctive differences, the heads may be misarranged because of similar colors thereof.
(3) In the manufacturing process of the monochromatic recording head having two or more liquid jet recording heads of different nozzle densities and similar appearance, it is difficult to distinguish those heads by shape or by color, and they may be misarranged.
(4) The above items (1) to (3) are not preferable in the process management and lead to an increase of the member of steps, the decrease of the yield, and the increase of the cost of the liquid jet recording head.